This invention relates to benzisoxazole derivatives. These compounds have selective 5-HT4 receptor agonistic activity. The present invention also relates to a pharmaceutical composition, method of treatment and use, comprising the above derivatives for the treatment of disease conditions mediated by 5-HT4 receptor activity; in particular 5-HT4 receptor agonistic activity.
In general, 5-HT4 receptor agonists are found to be useful for the treatment of a variety of diseases such as gastroesophageal reflux disease, gastrointestinal disease, gastric motility disorder, non-ulcer dyspepsia, functional dyspepsia, irritable bowel syndrome (IBS), constipation, dyspepsia, esophagitis, gastroesophageral disease, nausea, central nervous system disease, Alzheimer's disease, cognitive disorder, emesis, migraine, neurological disease, pain, cardiovascular disorders, cardiac failure, heart arrhythmia, diabetes, and apnea syndrome (See TiPs, 1992, 13, 141; Ford A. P. D. W. et al., Med. Res. Rev., 1993, 13, 633; Gullikson G. W. et al., Drug Dev. Res., 1992, 26, 405; Richard M. Eglen et al, TiPS, 1995, 16, 391; Bockaert J. Et al., CNS Drugs, 1, 6; Romanelli M. N. et al., Arzheim Forsch./Drug Res., 1993, 43, 913; Kaumann A. et al., Naunyn-Schmiedeberg's. 1991, 344, 150; and Romanelli M. N. et al., Arzheim Forsch./Drug Res., 1993, 43, 913).
There are no prior arts that describe compounds with the similar chemical structure and selective 5-HT4 receptor agonistic activity.
Then, benzisoxazole compounds with the similar chemical structure is disclosed in WO93/04063. Especially, a compound represented by the following formula is disclosed as Example 37. However, the compounds are acetylcholine esterase AChE inhibitors.

There is a need to provide new 5-HT4 agonists that can be good drugs. In particular, preferred compounds should bind potently to the 5-HT4 receptor whilst they show little affinity for other receptors and show functional activity as agonists. They should be well absorbed from the gastrointestinal tract, be metabolically stable and possess favorable pharmacokinetic properties. When targeted against receptors in the central nervous system they should cross the blood brain barrier freely and when targeted selectively against receptors in the peripheral nervous system they should not cross the blood brain barrier. They should be non-toxic and demonstrate few side-effects. Furthermore, the ideal drug candidate will exist in a physical form that is stable, non-hygroscopic and easily formulated.